👤

Efectuaţi:
5a+10a+15a+...+60a+3b+6b+9b+...36b


Răspuns :

=5a(1+2+3+....12)+3b(1+2+3+...12)
(1+2+....12)(5a+3b)=13*12/2(5a+3b)
=78(5a+3b)